Most internal combustion engines include intake and exhaust valves operated by cams located along a camshaft mounted generally along the length of the engine. Normally, the crankshaft is supported by a series of bearings resting in corresponding engine journals spaced axially along the length of the shaft. Each bearing is supported in its corresponding journal by a bushing which is replaceable should it become worn or damaged. Further, the bushing is normally located within the journal to align a butt joint seam or passage with a lubricating passage to allow lubrication fluid to pass from the engine to the bearing surface of the bushing. If the bearing becomes worn or damaged for any reason, such as a lubrication system failure, the bushings must be replaced.
In the past only primitive methods for installing and removing camshaft bushings were generally available. Initially, a hammer and chisel were used to remove old bushings while a hammer and mating block were used for installing new ones. This method proved to be unsatisfactory for servicing bushings due to the difficulty of reaching engine journals located deep within the engine. Further, the use of a hammer and block was not an extremely accurate way to insert a bushing and could result in damage to the bushing and/or engine block.
To overcome the problems associated with the use of these simple tools, more complex devices have been developed for removing and installing camshaft bushings U.S. Pat. No. 3,327,337 issued to German discloses a size adjustable tool for removing and installing cam shaft bushings including a puller rod on which a mandrel is slidable upon the rod to insert or remove a bushing from a bushing journal. Bushings are installed or removed by pulling the rod in the proper direction to accomplish the desired function. Moreover, the rod is pulled in a manual operation by a threaded portion at the end of the rod which is threadingly engaged with a nut and washer arrangement providing movement in one direction. However, due to the nature of differing engine bearing journals, it is sometimes beneficial to push some of the journal bushings into place while others are more desirably pulled. The same may be true for bushing removal. German does not allow such an operation using a single rod.
Attempts have been made to automate camshaft bushing removal and installation. U.S. Pat. No. 2,751,670 issued to Grad discloses a bushing assembly press which includes an hydraulic powered system for inserting a series of bushings into a plurality of journals all of which are in axial alignment. However, the system developed by Grad is a large, complicated system including several separate bushing rams mounted on a mechanism which rotates into alignment with the bushing bore to allow the hydraulic pushing means to insert each bushing into its appropriate journal Due to the large nature of this system, it is not appropriate for field servicing of bushings, nor does it provide a means of removing old bushings from their journals.
As stated above, it is also important when installing a camshaft bushing to properly align the oil supply opening in the wall of the bushing with the oil delivery passage of the engine block. U.S. Pat. No. 4,619,027 to Ohannesian discloses a tool for installing and aligning camshaft bushings including mandrels equipped with spring biased pins to align with the oil delivery system. The tool, however, requires manual hammering to install the bushing which may be hard to accurately control for journals located deep within the engine block. Also, the tool does not provide a means of removing old bushings.
Therefore, a simplified camshaft bushing removing and installing tool which is hydraulically powered would by beneficial to service technicians for use in the field. Particularly, desirable would be a tool which provides hydraulically powered motion in both a pushing and pulling mode for expedient camshaft bushing removal and installation.